Microsoft has mistakenly replaced Windows 11’s boot sound — in test versions of the OS — with the startup chime from Windows Vista.

Windows testers started noticing the issue shortly after Microsoft released its latest Dev Channel build of Windows 11 on Friday afternoon. The .WAV file for the bootup sound, which is stored inside imageres.dll, had been randomly replaced with the Windows Vista startup sound in preview build 26200.5651.

Microsoft quickly acknowledged the mistake, and added a line to its release notes for the latest Dev Channel build. “This week’s flight comes with a delightful blast from the past and will play the Windows Vista boot sound instead of the Windows 11 boot sound,” says the Windows Insider team. “We’re working on a fix.”

The Verge